Binary/Digital to Analogue Converter

MarkNightingale

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Guys,

I have googled this for about an hour now and can't find what I am looking for.

I need a module which will take 8 inputs, and convert this to a 0-10v signal.

Anyone used anything like this before?

Cheers

Mark
 
Are you saying you wish to use an 8 digital input and convert it to an analogue.
Is this a standalone thing or with a PLC. A bit more information would be helpful.
 
Hi Parky,

Yes its for a standalone system.

The PLC is already in place, but it is a B&R PLC and I currently don't have the software.

I have a pneumatic cylinder that uses a positioner to control tension on a roll.

At present this is done using an 8 bit binary make up from the PLC.

The cylinder is now obsolete, and the manufacturer have told me they can get me a 0-10v cylinder.

So I was looking at converting this binary position from the outputs of the PLC and convert it to 0-10v.

Cheers

Mark
 
Search for (I think it's called 1R, 2R ladder network) I have never seen a commercial unit so you may have to build one, I did this years ago using Cmos logic gates & a resistor ladder, Using a 12v feed to the PLC output card actually gave me 0-9.4 v if I remember correctly. It was a long time ago so cannot remember the circuit.
See this:
https://www.electronics-tutorial.ne...ital systems it should be converted to analog.
Also look at this:
https://microcontrollerslab.com/dac0832-8-bit-dac-pinout-example-applications-features/

I have had a quick search & I'm struggling to find a commercial unit but will have closer look
 
Just had a thought about it, I suppose you could just use resistors in a 1R,2R ladder network connected to a digital output card, I would try this using say a 12v supply to the card then see what output you get at 255 if it's 12v then you may have to reduce the supply to 10v. you probably do not need any amplification because you can use a supply to the card that suits.
Note though an 8 bit DAC will only give you 255 steps from 0-10v so a little crude but probably good enough.

Here is another paper on the subject.
http://ume.gatech.edu/mechatronics_course/DAC_S04.pdf
 
Cheap PLC with 8 inputs and an analog output? One line of code copying the digital input image to an INT, then scaling it to the analog output range.

Bit of a bludge though but i haven't come across anything that could do this out the box.
 
Yes but two problems it is no longer available and it's 4-20ma output
Here is a !R 2R ladder these need to be precision resistors and you may need to change them to lower values, I have just done an experiment but unfortunately I only have 47k & 22k so I padded the one to OV down to 22k it was not linear but gave me 0-10.53 volts from 0-255 onto a multi meter. but that is very high impedance .
The resistors need to be precision & exactly a ration of 2 to 1 i.e. 25k & 50k for it to work well.

r2r_dac-sch.png
 

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